#include "wn_tick.h"

static uint32_t sys_time = 0;
static volatile uint8_t tick_irq_flag;

void web_tick_inc(uint32_t tick_period)
{
    tick_irq_flag = 0;
    sys_time += tick_period;
}


uint32_t web_tick_get(void)
{
    uint32_t result;
    do {
        tick_irq_flag = 1;
        result        = sys_time;
    } while(!tick_irq_flag); /*Continue until see a non interrupted cycle */

    return result;
}

/**
 * Get the elapsed milliseconds since a previous time stamp
 * @param prev_tick a previous time stamp (return value of systick_get() )
 * @return the elapsed milliseconds since 'prev_tick'
 */
uint32_t web_tick_elaps(uint32_t prev_tick)
{
    uint32_t act_time = web_tick_get();

    /*If there is no overflow in sys_time simple subtract*/
    if(act_time >= prev_tick) {
        prev_tick = act_time - prev_tick;
    }
    else {
        prev_tick = UINT32_MAX - prev_tick + 1;
        prev_tick += act_time;
    }

    return prev_tick;
}

